Studies of Zeolite Acidity

该项目包括一系列针对这一问题的研究 沸石和相关材料的酸性。 中间体 在 H-ZSM-5分子筛的核磁共振波谱研究 共振是主要的工具-来描述那些 化学计量和反应性已分别建立; 目标是确定 中间体，它们与中间体相互作用的性质 沸石晶格，以及它们经历的势垒高度 进一步转型。 各种脱铝效果 程序以及框架和非框架的作用 铝浓度通过制备和 研究了一系列具有良好特征的 H-Y沸石;使用的酸度替代物包括温度- 程序脱附和热重分析 胺、烷烃裂解和碱金属中毒。 一系列 金属取代的ZSM-5和ALPO-5分子系列中， 制备并检查以确定相对酸强度 这些材料，并确定必要的条件 用于将金属离子保持在骨架中。 沸石已经广泛用于石油和天然气中， 化学工业作为催化剂和分离介质。 尽管如此，影响其业绩的因素很少， 明白 这项工作承诺的方法，以更合理的 沸石和相关框架的应用设计 材料，更好的合成沸石质量控制， 已知的或新的框架材料的可能的新应用 在化学处理、环境控制和其他 地区

This project consists of a set of studies addressing the issue of acidity in zeolites and related materials. Intermediates in H-ZSM-5 are studied spectroscopically - nuclear magnetic resonance being the prime tool - to characterize species whose stoichiometry and reactivity have been established separately; the objectives are the determination of the structure of the intermediates, the nature of their interactions with the zeolite lattice, and the barrier heights for them to undergo further transformations. The effect of various dealumination procedures and the roles of framework and nonframework aluminum concentrations are examined by preparation of and investigation of the acidity of a series of well-characterized H-Y zeolites; acidity surrogates used include temperature- programmed desorption and thermal gravimetric analysis of amines, alkane cracking, and alkali-metal poisoning. A series of metal-substituted ZSM-5 and ALPO-5 molecular series are prepared and examined to determine the relative acid strengths of these materials and to determine the necessary conditions for maintaining the metal ions in the framework. Zeolites are already widely used in the petroleum and chemicals industries both as catalysts and separations media. Despite this, factors influencing their performance are poorly understood. This work promises an approach to more rational design for applications of zeolites and related framework materials, better quality control over synthetic zeolites, and possible new applications of known or new framework materials in chemical processing, environmental control, and other areas.